The invention relates to reproducing apparatus for magnetic tape and particularly to such apparatus for use in commercial radio broadcasting where it may be required to operate continuously with the highest possible standards of reliability and durability.
Typically, such apparatus is selectively operable in at least three basic modes including play mode, fast forward mode, and fast rewind mode. Some have an additional edit mode in which the audio content of the tape can be scanned at fast speed. In the play mode, forward and rewind reels are simultaneously urged in opposite directions by forward and rewind torque motors to tension the tape, the tape lifter is in lowered position enabling the tape to engage the head, and the pressure roller presses the tape against the capstan to move the tape forward at a lineal speed determined by the rotational speed of the capstan. In either fast mode, the appropriate forward or rewind torque motor is energized, the tape lifter holds the tape off the head and the pressure roller is held spaced from the capstan to free the tape from the capstan and enable the tape to be moved at fast speed determined by the energized torque motor and the diameter of tape wrap on the driving reel. In edit mode, the tape is run at fast speed in pickup proximity to the head with the audio on enabling the operator to quickly scan the tape for the general location of a particular cut or selection. Thus, edit mode is a variation of fast mode with the audio circuit energized, and the proximity of the tape to the head may be variable to adjust the volume of the audio output for edit purposes.
Normally, for play mode and either fast mode, movements of the tape lifter and pressure roller may be automatically interrelated so that when the tape lifter is lowered to enable the tape to engage the head, the pressure roller presses the tape against the capstan; and when the tape lifter lifts the tape from the head, the pressure roller moves away from the capstan enabling the tape to run freely and rapidly past the capstan. But, for edit mode, there must be capability of manually overriding this relationship so the tape can be moved into engagement, or pickup proximity, with the head when the pressure roller is spaced from the capstan.
In conventional reproducing apparatus where the tape lifter and pressure roller are interrelated as described above, this is done by relatively complicated solenoid or mechanical arrangements which are costly to manufacture, not as long lasting and reliable as desired; and the means for overriding this relationship in edit mode is relatively complicated and not entirely satisfactory.